Air inlet system for an internal combustion engine

ABSTRACT

An air inlet system for an internal combustion engine includes an inlet duct for furnishing air to the engine&#39;s cylinders, and a combination port formed within the inlet duct for inducting both recirculated exhaust gas and charge air into the engine. Mixing of the recirculated exhaust gas and the charge air is promoted by a flow director which is mounted at a downstream end of an EGR supply passage, as well as by a flow guide mounted upstream from the flow director, with the flow guide including an aerodynamic projection for causing charge air to move smoothly around the flow director and a swirl generator.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates to an air inlet system for furnishing chargeair, including recirculated exhaust gas, to the cylinders of areciprocating internal combustion engine.

2. Related Art

Diesel engines, while offering excellent fuel economy, must becontrolled ever more stringently in terms of exhaust emissions,particularly oxides of nitrogen (NOx) and particulate matter. In aneffort to control NOx without causing an undue loss in fuel economy,engine designers have relied upon increasingly higher amounts of exhaustgas recirculation (EGR). More specifically, EGR rates of approximately30% at peak power conditions and 60% at low speed load are on thehorizon. Unfortunately, it is difficult to furnish very high amounts ofEGR to an engine's cylinders in a uniform manner; in other words,without providing too much EGR to one cylinder while too little toothers. Maldistribution of EGR causes an engine to run rough and withunacceptable emissions. Although an extremely lengthy intake tract maybe used to provide adequate mixing of EGR with the other components ofcharge air, a long intake tract may not be feasible, particularly in avehicular application.

It would be desirable to provide an inlet system for an internalcombustion engine, such as a diesel engine, having the capability offully mixing large amounts of EGR in a charge air stream to prepare auniform mixture for induction into the engine's power cylinders.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the present invention, an air inlet system foran internal combustion engine includes an inlet duct for furnishing airinto the engine's cylinders, and a combination port, formed in the inletduct, for inducting both recirculated exhaust gas and charge air into anengine. An EGR injector mounted within the combination port includes acentral EGR supply passage extending generally parallel to the directionof charge air flow entering the combination port, and a flow directormounted at a downstream end of the EGR supply passage. The flow directorand EGR supply passage cooperate to define an annular EGR dischargeorifice.

According to another aspect of the present invention, a flow guide ismounted upstream from the flow director, with the flow guide including agenerally ogive-shaped, aerodynamic projection for causing charge air tomove smoothly around the flow director. The flow guide also includes aswirl generator with a number of radially directed vanes, with each ofthe vanes having at least a first end joined to the generallyogive-shaped projection and with the vanes adapted to impart a swirlingmotion to charge air, including EGR, flowing through the combinationport.

According to another aspect of the present invention, the radiallydirected vanes of the swirl generator each have a first end joined tothe generally ogive-shaped projection and a second end attached to aperipheral ring.

According to another aspect of the present invention, the flow directorand the central EGR passage are configured to cause recirculated exhaustgas to enter the combination port radially.

According to another aspect of the present invention, the EGR supplypassage may be equipped with an integral one-piece bulkhead having anogive-shaped projection similar to the shape of the previously describedflow guide, with the EGR supply passage also having a number of radiallydirected discharge orifices for causing EGR flow into a combination portin a radially directed direction.

It is an advantage of an air induction system according to the presentinvention that EGR will be introduced not only into the core portion ofthe air flowing into the engine, but also into the boundary, or moreremote, portions of the flow, so as to promote an even distribution ofEGR to the engine's cylinders.

It is another advantage of a system according to the present inventionthat pressure drop on both the EGR and charge air sides of the inductedgases will be reduced, as compared with known EGR systems, whileallowing for both smaller package dimensions for the air inductionsystem and excellent mixing of EGR gases with the charge air.

It is yet another advantage of a system according to the presentinvention that an engine equipped with this system may be optimized forminimum exhaust emissions because of the more finely regulated and evendistribution of EGR to the engine's various cylinders.

It is yet another advantage of the present invention that, as a resultof more even EGR flow to each cylinder, the cylinders will developnearly identical peak pressures, permitting the engine to be calibratedat peak power to take maximum advantage of each cylinder instead ofbeing restricted because of maldistribution in the cylinder pressures.

It is yet another advantage of a system according to the presentinvention that fuel economy will be improved because of the absence of aneed to retard injection timing with a diesel engine to achieve mandatedNOx levels.

It is yet another advantage of a system according to the presentinvention that the noise, vibration, and harshness (NVH) of an enginewill be improved with the present system because even distribution ofEGR will prevent discordant sounding combustion.

Other advantages, as well as features of the present invention, willbecome apparent to the reader of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a air inlet system accordingto an aspect of the present invention.

FIG. 2 illustrates a partially assembled air inlet system according toan aspect of the present invention.

FIG. 3 illustrates a frontal perspective view of a flow guide accordingto an aspect of the present invention.

FIG. 4 is a perspective view of the flow guide of FIG. 3, but in a rearview.

FIG. 5 is a perspective view of an air inlet system, according to thepresent invention, showing a combination of the EGR handling portion anda throttle body.

FIG. 6 is similar to FIG. 5, but shows a cantilevered EGR supply tubewith a one-piece flow guide and a number of orifices for radialinjection of EGR into charge air flowing from the throttle body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, air inlet system 10 includes an inlet duct, 14,having a dividing wall, 18, which separates duct 14 into bifurcatedducts 14 a and 14 b. Ducts 14 a and 14 b furnish air to different banksof a multi-bank reciprocating internal combustion engine. Those skilledin the art will appreciate, in view of this disclosure, however, thatthe present air inlet system may be employed with inline engines, inwhich case the bifurcation illustrated in inlet duct 14, includingpartial dividing wall 18, may be rendered unnecessary.

FIG. 1 shows with particularity throttle body 54, which may be either amanual or an electronically controlled throttle body, with the latterbeing illustrated. Throttle body 54 is attached to an adapter, 50, whichfunctions to sandwich a flow guide 36 between throttle body 54 andcombination port 22 of inlet duct 14. Throttle body 54 has a throttlevalve, 56, shown in FIGS. 1, 5, and 6.

The precise mounting arrangement of flow guide 36 and adapter 50 areshown in FIG. 2, along with a perspective view of combination port 22.FIG. 5 illustrates further details of the placement of variouscomponents according to the present invention. Thus, combination port 22is shown as being entered by an EGR injector including EGR supplypassage 26, which extends in a direction generally parallel to chargeair entering combination port 22. EGR supply passage 26 may be furnishedwith EGR controlled by an EGR valve in a manner known to those skilledin the art and suggested by this disclosure.

As shown in FIG. 5, downstream end 26 a of EGR supply passage 26cooperates with flow director 30 to define an annular EGR dischargeorifice, 34, which is shown as allowing a radially directed flow of EGRinto the charge air flowing through combination port 22. This radiallydirected flow of EGR assures even mixing of the EGR with the charge air,producing the benefits recited earlier in the specification.

As shown in FIGS. 3 and 4, flow director 30 is joined with andincorporated within flow guide 36, which includes an aerodynamic,generally ogive-shaped projection, 38, which causes charge air to flowsmoothly around EGR supply passage 26, mitigating the pressure drop towhich the charge air would otherwise be subjected. On the other hand,the smooth transition into annular orifice 34 provided by flow director30 reduces the EGR pressure drop within EGR passage 26, therebypromoting the high EGR mass flow levels achievable by the presentsystem.

Flow guide 36 also includes a number of swirl vanes, 42, with each ofthe vanes having a first end joined to generally ogive-shaped projection38, and having a second end attached to a peripheral ring, 46, whichfacilitates the mounting of flow guide 36 into combination port 22, withthe retention being provided by throttle body adapter 50. Although swirlvanes 42 provide excellent mixing, with certain applications having asufficiently long mixing length, the vanes may not be required.

In the event that inlet passage 14 may be configured with a longermixing length for a particular engine, the configuration illustrated inFIG. 6 may be employed. In FIG. 6, EGR is discharged through a number ofradially directed orifices 62, with EGR supply passage 26 having aunitary bulkhead, 31, surmounted by an ogive-shaped projection, 71, inthe manner of projection 38. In the embodiment of FIG. 6, EGR supplypassage 26 is cantilevered into generally cylindrical combination port22 and extends axially and generally parallel to the direction of chargeair flow. Because of the longer mixing length, swirl vanes 42 andperipheral ring 46 are eliminated.

The foregoing invention has been described in accordance with therelevant legal standards, thus the description is exemplary rather thanlimiting in nature. Variations and modifications to the disclosedembodiment may become apparent to those skilled in the art and fallwithin the scope of the invention. Accordingly the scope of legalprotection afforded this invention can only be determined by studyingthe following claims.

1. An air inlet system for an internal combustion engine, comprising: aninlet duct for furnishing charge air to engine cylinders; a combinationport formed in said inlet duct for inducting both recirculated exhaustgas and charge air into an engine; an EGR injector mounted within saidcombination port, with said EGR injector comprising: a central EGRsupply passage extending generally parallel to the direction of saidcharge air entering said combination port; and a flow director mountedat a downstream end of said EGR supply passage and, in combination withsaid EGR supply passage, defining an annular EGR discharge orifice; anda flow guide mounted upstream from said flow director, with said flowguide comprising: a generally ogive-shaped projection for causing chargeair to move smoothly around said flow director; and a swirl generatorcomprising a plurality of radially directed vanes, with each of saidvanes having at least a first end joined to said generally ogive-shapedprojection, with said vanes adapted to impart a swirling motion tocharge air flowing through said combination port.
 2. An air inlet systemaccording to claim 1, wherein said radially directed vanes of said swirlgenerator each comprise a first end joined to said generallyogive-shaped projection and a second end attached to a peripheral ring.3. An air inlet system according to claim 1, further comprising athrottle body attached to said air inlet duct upstream from said flowguide.
 4. An air inlet system according to claim 1, wherein said inletduct is bifurcated downstream from said combination port.
 5. An airinlet system according to claim 1, wherein said flow director, saidgenerally ogive-shaped projection, and said swirl generator are onepiece.
 6. An air inlet system according to claim 1, wherein said flowdirector and said generally ogive-shaped projection are one piece.
 7. Anair inlet system according to claim 1, further comprising anelectronically controlled throttle body attached to said air inlet ductimmediately upstream from said flow guide.
 8. An air inlet systemaccording to claim 1, wherein said flow director and said central EGRpassage are configured to cause recirculated exhaust gas to enter saidcombination port radially.
 9. An air inlet system for an internalcombustion engine, comprising: an inlet duct for furnishing charge airto engine cylinders; a combination port formed in said inlet duct forinducting both recirculated exhaust gas and charge air into an engine;an EGR injector mounted within said combination port, with said EGRinjector comprising: a central EGR supply passage extending generallyparallel to the direction of said charge air flow through saidcombination port; and a flow director mounted at a downstream end ofsaid EGR supply passage and, in combination with said EGR supplypassage, defining an annular EGR discharge orifice, with said EGR supplypassage and said flow director cooperating to cause recirculated exhaustgas to enter said combination port radially; and a flow guide formed asone piece with said flow director, with said flow guide being locatedupstream from said flow director, with said flow guide comprising: anaerodynamic projection for causing charge air to move around said flowdirector; and a swirl generator comprising a plurality of radiallydirected vanes, with each of said vanes having a first end joined tosaid aerodynamic projection and a second end joined to a commonperipheral ring, with said vanes adapted to impart a swirling motion tocharge air flowing through said combination port.
 10. An air inletsystem for an internal combustion engine according to claim 9, whereinsaid one-piece flow director and flow guide are retained within saidcombination port by an adapter which is configured for mounting athrottle body.
 11. An air inlet system for an internal combustion engineaccording to claim 10, further comprising a throttle body mounted tosaid adapter.
 12. An air inlet system for an internal combustion engineaccording to claim 11, wherein said throttle body comprises anelectronically controlled throttle body.
 13. An air inlet system for aninternal combustion engine according to claim 9, wherein saidaerodynamic projection is generally ogive-shaped.
 14. An air inletsystem for an internal combustion engine, comprising: an inlet duct forfurnishing charge air to engine cylinders; a combination port formed insaid inlet duct for inducting both recirculated exhaust gas and chargeair into an engine; a one-piece EGR injector mounted within saidcombination port, with said EGR injector comprising: a central EGRsupply passage extending generally parallel to the direction of saidcharge air flow through said combination port; and an integral, unitary,flow director incorporated in a bulkhead mounted at a downstream end ofsaid EGR supply passage and, in combination with said EGR supplypassage, defining a plurality of EGR discharge orifices, with saidorifices causing recirculated exhaust gas to enter said combination portradially; and a flow guide configured as one piece with said flowdirector, with said flow guide being located upstream from said flowdirector, with said flow guide comprising: an aerodynamic projection forcausing charge air to move around said flow director; and a swirlgenerator comprising a plurality of radially directed vanes, with eachof said vanes having a first end joined to said aerodynamic projectionand a second end joined to a common peripheral ring, with said vanesadapted to impart a swirling motion to charge air flowing through saidcombination port.
 15. An air inlet system according to claim 14, whereinsaid aerodynamic projection is ogive-shaped.
 16. An air inlet system foran internal combustion engine, comprising: an inlet duct for furnishingcharge air to engine cylinders; a generally cylindrical combination portformed in said inlet duct for inducting both recirculated exhaust gasand charge air into an engine; a one-piece EGR injector mounted withinsaid combination port, with said EGR injector comprising: a central EGRsupply passage cantilevered axially into said combination port andextending generally parallel to the direction of said charge air flowthrough said combination port; and an integral, unitary, flow directorincorporated in a bulkhead mounted at a downstream end of said EGRsupply passage and, in combination with said EGR supply passage,defining a plurality of EGR discharge orifices, with said orificescausing recirculated exhaust gas to enter said combination portradially, with said flow director further comprising a generallyogive-shaped aerodynamic projection for causing charge air to movesmoothly around said flow director.
 17. An air inlet system according toclaim 16, further comprising a flow guide configured as one piece withsaid flow director, with said flow guide being located upstream fromsaid flow director, with said flow guide comprising a swirl generatorcomprising a plurality of radially directed vanes, with each of saidvanes having a first end joined to said generally ogive-shapedprojection and a second end joined to a common peripheral ring, withsaid vanes adapted to impart a swirling motion to charge air flowingthrough said combination port.